Put a baking sheet in the oven and preheat to 450 degrees F. Toss the squash with 1 tablespoon olive oil, 1/2 teaspoon salt and a few grinds of pepper and spread in a single layer on the hot baking sheet. Roast until the squash is tender and browned on the bottom, about 20 minutes.
Meanwhile, chop the celery and red onion and set aside. Heat 1 tablespoon olive oil in a large nonstick skillet over high heat. Season the pork with salt, pepper and 1 tablespoon thyme. Add
2 pork scallopini to the skillet and cook, turning once, until browned and just cooked through, about 3 minutes. Remove to a plate and cover to keep warm. Add 1 more tablespoon oil to the skillet and repeat with the remaining pork.
Add the remaining 1 tablespoon oil, the celery, red onion and 1/4 teaspoon salt to the skillet. Cook, stirring, until crisp-tender, about 3 minutes. Add the garlic, capers and remaining 1 tablespoon thyme and cook, stirring, until the garlic is golden, about 3 minutes. Add the squash, vinegar, sugar and 1/4 cup water and cook until the liquid is almost absorbed, 1 to 2 minutes. Season with salt and pepper and stir in the basil. Divide the pork and vegetables among plates.